This invention relates generally to a system for warning a site of the relative approach of a dangerous situation, such as an emergency vehicle or another emergency situation such as a fire. More specifically, this relates to a site, such as an emergency vehicle, equipped with an electronic signal transmitter emitting an signal containing a message. Preferably, this signal is an electromagnetic frequency signal, preferably a radio frequency. Another site, such as another vehicle, is equipped with a receiver alert system that warns an operator of the other site when a probability of a dangerous situation, such as a collision, exists.
For example, to assure right-of-way to approaching emergency vehicles, these emergency vehicles are equipped with audible and visual warning devices such as sirens and flashing red lights. Other motor vehicles nearby an approaching emergency motor vehicle can act accordingly and provide a safe right-of-way for the emergency vehicle once the drivers of those other vehicles are aware of the siren and/or flashing lights of the approaching emergency vehicle.
A timely warning especially depends on upon a driver""s ability to hear an emergency vehicle siren that is external to and disconnected from the passenger compartment of the vehicle to be warned. Improved vehicle construction with respect to passenger compartment soundproofing, an increased ambient noise within the passenger compartment due to car radios and stereos, ventilation fans, and alike, have made it more difficult for the driver to hear the audible siren warning of an approaching emergency vehicle. This increases the probability that a clear right-of-way may be delayed for the emergency vehicle. Further, dangerous traffic conditions can arise when an unwarned driver obstructs an emergency vehicle that is often traveling at high speed.
In addition, other dangerous situations do not give notice to vehicles of the dangers associated with them. For example, an operator of a vehicle has no way of knowing that he is approaching a toxic fire or other hazard. A way of warning sites of dangerous situations their relative location, and a relative velocity is needed.
U.S. Pat. No. 3,673,560, Max, et al., reveals a vehicle alerting system comprising a transmitter in an emergency vehicle and a receiver in another vehicle. The receiver has a single antenna, which is designed to pick up a transmitted code from the transmitter on the emergency vehicle. Response to the signal from the emergency vehicle transmitter include both visual and audible outputs.
In U.S. Pat. No. 3,760,349, Keister, et al., reveals another emergency warning system. Keister discloses a transmitter mounted in an emergency vehicle. The transmitter transmits a specific code sequence of signals.
A receiver in each private car is designed to respond only to these signals. Response to these signals includes both light and audio indication. The receiver also includes a way to decode the incoming signals. Each separate decoded signal has a distinct alarm signal associated with a different emergency situation.
U.S. Pat. No. 3,784,970, Simpkin, et al., discloses a range-controlled emergency vehicle warning system with a directional radio frequency transmitter. The transmitter transmits general warning and advisory information on a radio frequency signal. The transmitter is limited to a controlled zone in front of the vehicle having a transmitter.
In U.S. Pat. No. 3,997,868, Ribnick, et al., an emergency vehicle contains a transmitter. The transmitter is connected to a directional device such as a compass. Depending upon the orientation of the directional travel of the emergency vehicle, the device generates a tone indicating the direction of travel of the emergency in an omni-directional manner. A receiver in another vehicle receives the radio frequency generated by the transmitter in the emergency vehicle. A particular tone frequency activates a set of lights carried by the receiving vehicle and indicates the direction of travel of the emergency vehicle. The driver of the second vehicle can then determine the relative direction of the emergency vehicle by comparing the emergency vehicle travel direction with his own travel direction.
In U.S. Pat. No. 4,238,778, Oshumi, discloses an electronic transmitter receiver system for warning a motor vehicle driver of the approach of an emergency motor vehicle. The emergency vehicle is equipped with a short range radio frequency transmitter. The transmitter is omni-directional. Oshumi uses the amplitude of the signal to initiate a warning signal within the second vehicle. As the relative distance between the two vehicles decreases, the strength of the warning signal increases, and vice versa. The entire apparatus only warns a second vehicle when the received radio signal is above a predetermined intensity.
In U.S. Pat. No. 4,403,208, Hodgson, discloses a vehicle warning system. Hodgson discloses a means for using the Doppler effect of a transmitted signal to indicate whether the vehicle carrying the transmitter is approaching or receding. When the transmitted radio frequency bearer is determined as receding from the receiver, the unit will shut it out. Hodgson also discloses a means by which the warning in the second vehicle is activated based upon the velocity of the transmitter towards the receiver.
However, Hodgson gives no indication of the velocity, meaning a speed and direction, of the transmitting vehicle. It only gives a relative distance, and no indication of the direction or location of the transmitting vehicle.
U.S. Pat. No. 4,794,394, Halstead, discloses emergency vehicle proximity warning system. Halstead discloses a transmitter carried on an emergency vehicle and receiver carried onboard a second vehicle. The transmitter modulates and transmits a continuing stream of equally timed spaced pulses. The receiver on the second vehicle receives the radio signal. It determines then whether the continuous stream of equally timed space pulses from the transmitter is present. If the timed spaced pulses are present, they start an alarm within the vehicle.
U.S. Pat. No. 5,307,060, Prevulsky, et al., discloses an emergency vehicle alert system whereby an emergency vehicle contains a transmitter. The emergency vehicle transmits an alert signal including an emergency vehicle type code. The second vehicle contains a receiver for receiving the radio pulses from the transmitter contained in the emergency vehicle. The second vehicle system then stores the codes to a stored set of type signals and alerts the driver accordingly.
In U.S. Pat. No. 5,572,201, Graham, et al., discloses another alerting device for abnormal situations. Again, an emergency vehicle contains an active radio transmitter. The transmitter emits a range limited signal. The transmitter onboard the emergency vehicle includes an automatic gain control that responds to the speed of the emergency vehicle to control the range of the transmitted signals in relation to the speed of the vehicle. Graham also discloses a way to shape the radiation pattern of the emergency signals broadcast by the transmitter, especially backwards and forwards. Graham also discloses sensors onboard emergency vehicles providing information regarding the speed, direction, and instantaneous position of the vehicle. This information is relayed and decoded to provide a visual display of the position, direction, and speed of the transmitting vehicle. Graham discloses the emergency vehicle receiving information describing the directional heading of the emergency vehicle from a compass. This information is encoded and transmitted to other emergency vehicles for other vehicles containing a receiver equipped to decode it.
All of the noted prior art deals with only half of the true picture of the situation. Both the transmitting and receiving vehicles have velocities, meaning a speed and a direction. A more accurate determination of the possibility of collision is available when one knows the location of the transmitting vehicle. In addition, further accuracy is achieved when the relative velocity, both speed and direction, of the transmitting vehicle is determined with respect to the receiving vehicle. If one can determine the location and relative velocity of the transmitting vehicle, a designer can implement a more precise warning system, thus making the warning system more effective.
None of these systems can determine the possibility of collision based upon true velocity or location measurements. A velocity measurement means that a one determines both the speed and direction of the vehicles. None of the prior art makes these determinations. None of the prior art allows for a direct calculation of the possibility of collision based upon the relative velocity of the transmitting vehicles with respect to the receiving vehicle. Additionally, none of the prior art makes a determination of the relative location of the transmitting vehicle with respect to the receiving vehicle.
What is needed is a vehicle alarm that actively computes the speed and direction of an oncoming emergency vehicle. What is needed is a vehicle alarm that actively determines whether the driver of the second vehicle needs to be warned based on the velocity of the transmitting vehicle, and on the velocity of the receiving vehicle. Additionally, what is needed is a vehicle alarm that calculates the relative location, and not just the distance, of a transmitting vehicle with respect to the receiving vehicle. Based on these conditions, a more accurate determination of the possibility of a collision can be made and relayed to a driver.
The present invention is directed toward a danger warning system in which passive and active inputs are used to alert an operator of a site, such as a vehicle, to the presence of dangerous situations, such as an oncoming emergency vehicle or other dangerous situation. The invention also determines whether there is a significant danger to the operator based on the proximity of the danger and the relative velocity of the danger to the receiving site.
The danger alert system comprises a signal transmitter about a site signifying danger. Preferably, the system comprises an electromagnetic frequency transmitter mounted about the site. One should note that the invention is not limited to dynamic and moving sites, such as emergency vehicles, but can be associated with a static site signifying a risk of danger, such as the location of construction or an ongoing fire.
The signal transmitter is connected to an antenna that broadcasts a signal outwards from the site. A site may have a speed sensor, a direction sensor, or a position sensor associated with it. These sensor outputs are connected to the signal transmitter in order that the information derived from them may be broadcast with the signal output by the signal transmitter. Preferably, this information is broadcast in the form of a message.
An encoder bridges the signal transmitter and the sensor output. The encoder serves to put the data obtained by the sensors into a form suitable for broadcasting via the signal transmitter.
The encoder also accesses a unique site identification code. The encoder may contain the unique site identification code, or an external source may supply this to the encoder. An additional input may be provided by the site indicating an extremely dangerous situation, such as a hot pursuit of another vehicle by an emergency vehicle.
Describing the preferred embodiment, the sensor readings, the unique site identification code, and the indication of an extremely dangerous situation, if not already in a digital format, are digitized and stored as a digital data message. Regular spaced timing digits are placed at the front of the digital data message. The encoder then encodes the entire digital message into an analog message representative of the digital message. This message is directed towards a signal transmitter generator where it is transmitted. In the preferred embodiment, the signal transmitter generates an electromagnetic signal, and the message is modulated and output as an electromagnetic frequency signal. In this embodiment, a very precise wavelength controller, such as a crystal oscillator, directs the operation of the electromagnetic frequency signal generator.
Controlled inputs from the transmitting site, such as a siren or warning light of an emergency vehicle, may turn the signal transmitter on and off. This enables or disables the transmission of the signal.
Further, the gain of the signal transmitter is increased as the site speeds up. Thus, the effective broadcast range of the signal transmitter is increased to compensate for the site""s increased rate of speed.
In a preferred embodiment, an amplitude detector monitors the output amplitude of the transmitted signal and assigns a value corresponding to the output amplitude. A feedback loop connects the amplitude detector with the encoder. The feedback loop makes the monitored amplitude value of the transmitted signal available to the encoder, which inserts the monitored amplitude value of the transmitted signal into the next message set for transmission. Thus, the next transmitted message contained in the transmitted signal will contain information about the amplitude of the previous transmitted signal.
Other sites are equipped with a receiver alert system. In this receiver alert system, tuners are prepared to receive a transmitted signal on the appropriate frequency. The tuners are connected to a plurality of signal receptors, such as antennae, placed around the site at a fixed and known distance from one another. In the case where the receiving site is a vehicle, in a preferred embodiment the signal receptors are placed on the vehicle and in close proximity to the four corners of the vehicle. In another preferred embodiment, signal receptors are placed at different heights on or about the receiving site. Using the spatial distance of the signal receptors, the system determines a relative location, meaning direction and distance, to the transmitting vehicle from the receiving vehicle based on the phase differences of the incoming signal at each of the signal receptors.
The receiver alert system contains a velocity measurer for measuring the relative velocity of the transmitting site. The receiver alert system also contains a site locator for determining the relative position of the transmitting site. These components determine the relative position and velocity of the transmitting site by analyzing the transmitted signal, and the message contained therein.
In addition, in the preferred embodiment, the receiver alert system is equipped with a precise frequency detector, such as one controlled by a crystal oscillator. A relative velocity of the transmitting vehicle may be determined from differences in received and transmitted wavelengths, or Doppler shift, of the incoming transmitted signal at each of the signal receptors.
The incoming message contained within the transmitted signal is then extracted from the transmitted signal. In the preferred embodiment, the transmission amplitude of the previous transmitted signal is extracted, along with the unique site identification code. In addition, the site""s speed and its direction of travel may also be extracted. The amplitude of the previous transmitted signal is compared to the received signal amplitude, and an estimate of the distance from the receiving site to the transmitting site is made. In addition, any changes in distance can be used to cross check previous velocity determinations. In the preferred embodiment, these parameters are made available to an onboard CPU which aids in the determination.
In the preferred embodiment, the CPU serves as a velocity measurer, a site locator, and a danger assessor.
If the transmitting site has broadcast previous messages, the relative velocity and location as determined by the phase difference of the transmitted signal at the signal receptors and the Doppler shift of the transmitted signal are rechecked. The differences in relative location between the previous signal and the current signal are checked against a direct measurement of the relative velocity of the transmitting site based on the Doppler shift of the signal at each of the signal receptors.
This is also checked against the distance. The current transmitted signal contains information about the amplitude of the previous signal. The fall off in amplitude of the signal as received versus the amplitude as broadcast gives an indication of the distance between the transmitting site and the receiving site as of the previous signal.
In the preferred embodiment, the invention also links the CPU to both a direction and speed sensor associated with the receiving site. The invention assesses the danger posed by the transmitting site to the receiving site. In the preferred embodiment, the invention determines a zone of safety around the receiving site. This zone is dynamic and is responsive to the receiving site""s speed and direction of travel. Based on the relative velocity of the transmitting site with respect to the receiving site, the invention calculates whether a the transmitting site will violate the zone of safety.
When the invention indicates that the transmitting site will violate the zone of safety within a certain time, the invention causes an alert to broadcast on an alert system indicating that the transmitting site poses a possible danger to the receiving site. The alert system is made up of both audio and visual indicators. These indicators serve to tell the relative direction of the transmitting site, the relative distance, and the degree of danger posed by the transmitting site.